Doc-test in busmapping has to be disabled

[noel2004]

PR #767 enable CircuitBuilder in busmapping setting up a full witness building from l2 trace (including mpt). As the result, busmapping would depend on mpt-zktrie crate and it cause doc-test can not be run since zktrie has induced a shared library dependence for libzktrie.so.

This is a Cargo issue which affect doc-test only (common lib test is not affected). Current we have no suitable way to remedy the problem except for adding no_run attr on the doc test, which stop the doc-test being run.

Prepare the libzktrie.so and specify the LD_LIBRARY_PATH for the path of the shared libs can also be a work-around but it is not recommended for CI. We may have some ways to handle this issue in the future if Cargo can not fix their issue yet:

1. We can make use some features and specify zktrie being built as static library under testing
2. The plan for a rust-base zktrie may also be a resultion.